Higher rates of cefiderocol resistance among NDM producing <i>Klebsiella</i> bloodstream isolates applying EUCAST over CLSI breakpoints
Burcu Isler, Cansel Vatansever, Berna Özer, Güle Çınar, Abdullah Tarık Aslan, Caitlin Falconer, Michelle J. Bauer, Brian M. Forde, Funda Şimşek, Necla Tülek, Hamiyet Demirkaya, Şirin Menekşe, Halis Akalın, İ̇lker İnanç Balkan, Mehtap Aydın, Elif Tükenmez Tigen, Safiye Koçulu Demir, Mahir Kapmaz, Şiran Keske, Özlem Doğan, Çiğdem Arabacı, Serap Yağcı, Gülşen Hazırolan, Veli Oğuzalp Bakır, Mehmet Gönen, Neşe Saltoğlu, Alpay Azap, Özlem Kurt Azap, Murat Akova, Önder Ergönül, Füsun Can, David L. Paterson, Patrick N. A. Harris
Abstract
BACKGROUND: spp. (CRK) with higher MICs against metallo-beta-lactamase producers. There is a variation in cefiderocol interpretive criteria determined by EUCAST and CLSI. Our objective was to test CRK isolates against cefiderocol and compare cefiderocol susceptibilities using EUCAST and CLSI interpretive criteria. METHODS: = 254) of mainly OXA-48-like- or NDM-producing CRK bloodstream isolates were tested against cefiderocol with disc diffusion (Mast Diagnostics, UK). Beta-lactam resistance genes and multilocus sequence types were identified using bioinformatics analyses on complete bacterial genomes. RESULTS: Median cefiderocol inhibition zone diameter was 24 mm (interquartile range [IQR] 24-26 mm) for all isolates and 18 mm (IQR 15-21 mm) for NDM producers. We observed significant variability between cefiderocol susceptibilities using EUCAST and CLSI breakpoints, such that 26% and 2% of all isolates, and 81% and 12% of the NDM producers were resistant to cefiderocol using EUCAST and CLSI interpretive criteria, respectively. CONCLUSIONS: Cefiderocol resistance rates among NDM producers are high using EUCAST criteria. Breakpoint variability may have significant implications on patient outcomes. Until more clinical outcome data are available, we suggest using EUCAST interpretive criteria for cefiderocol susceptibility testing.